[dsymutil] Avoid relocating DW_AT_call_pc twice

Summary:
Avoid relocating DW_AT_call_pc, e.g. when a call PC is equal to the
function's low_pc as is the case in the test:

```
__Z5func1v:
0000000100007f94        b       __Z5func2v
```

rdar://62952440

Reviewers: friss, JDevlieghere

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79536

llvm/lib/DWARFLinker/DWARFLinker.cpp

@@ -1344,6 +1344,8 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
                                           std::numeric_limits<uint64_t>::max());
     AttrInfo.OrigCallReturnPc =
         dwarf::toAddress(InputDIE.find(dwarf::DW_AT_call_return_pc), 0);
+    AttrInfo.OrigCallPc =
+        dwarf::toAddress(InputDIE.find(dwarf::DW_AT_call_pc), 0);
   }
 
   // Reset the Offset to 0 as we will be working on the local copy of

llvm/test/tools/dsymutil/ARM/call-pc-reloc.test

@@ -0,0 +1,20 @@
+Instructions to reproduce
+-------------------------
+
+$ cat main.cpp
+void __attribute__((optnone)) func2() {}
+void __attribute__((noinline)) func1() { func2(); /* tail */ }
+int __attribute__((disable_tail_calls)) main() {
+  func1(); /* regular */
+  return 0;
+}
+
+# Adding `-isysroot $(xcrun -sdk iphoneos.internal -show-sdk-path)` can fix
+# linker warnings when building on macOS.
+$ clang -arch arm64 main.cpp -o main.arm64.o -c -g -O2
+$ clang -arch arm64 main.arm64.o -o main.arm64 -g
+
+RUN: dsymutil -oso-prepend-path %p/../Inputs %p/../Inputs/private/tmp/call_pc/main.arm64 -o %t.dSYM
+RUN: llvm-dwarfdump %t.dSYM | FileCheck %s -implicit-check-not=DW_AT_call_pc
+
+CHECK: DW_AT_call_pc (0x0000000100007f94)